Smart-cut technology is a process for forming semiconductor-on-insulator (SOI) constructions. An example process sequence that may be utilized in smart-cut technology is described by Bruel (M. Bruel, Electronics Letters, Jul. 6, 1995; Vol. 31, No. 14, pp 1201-1202). The process sequence comprises formation of silicon dioxide over a first monocrystalline silicon wafer, followed by implantation of hydrogen ions into the wafer to form a damage region. The damage region is spaced from the silicon dioxide by an intervening portion of the monocrystalline silicon material of the wafer. Subsequently, the wafer is bonded to a handle component (which can be a second semiconductor wafer) by hydrophilic bonding through the silicon oxide. The damage region is then thermally treated with a two-phase process. The two-phase process comprises first heating the damage region to a temperature of from about 400° C. to about 600° C. to split the wafer along the damage region (forming an SOI structure having a thin layer of monocrystalline bonded to the handle portion, and also forming a second structure corresponding to monocrystalline silicon which can be recycled into the process as a starting monocrystalline silicon wafer). The two-phase process then comprises heating the SOI structure to a temperature of greater than or equal to 1000° C. to strengthen chemical bonds. Although Bruel states that the first phase of the thermal treatment utilizes a temperature of from about 400° C. to about 600° C., it has been determined subsequent to Bruel that the first phase may be conducted utilizing a temperature of from about 200° C. to about 600° C.; and specifically that co-implants can be utilized to reduce the temperature utilized for such first phase.
Subsequent processing of the SOI structure may comprise chemical-mechanical polishing (CMP) to reduce surface roughness along an outer surface of the thin layer of monocrystalline silicon (i.e., along the surface that had formed during the break along the damage region).
Existing smart-cut processes can be expensive due to the large amount of hydrogen utilized in forming the damage regions. Another problem with existing smart-cut processes can be that the surface formed by breaking the damage region may be very rough, so that extensive CMP is required, which can reduce throughput and increase costs.
For the above-discussed reasons, it would be desirable to develop new smart-cut-type processes which can utilize less hydrogen than existing processes and/or which may have improved surfaces formed along the damage regions to reduce, or possibly even eliminate, subsequent CMP of such surfaces.